Apr. 29, 2008 The idea of going blind is a frightening thought for anyone. Recent work to restore visual function during retinal degenerative diseases resulting in complete loss of photoreceptors that enable vision, has created hope that retinal diseases leading to blindness may one day be reversed.
Dalhousie Neuroscience Professor Dr. Gautam Awatramani and colleagues have recently restored visual functions in mice in a lab in Switzerland. Dr. Awatramani and his colleagues triggered vision in diseased retina with light and now their work has been published in the journal Nature Neuroscience. The researchers successfully restored visual functions in mice with retinal degeneration disease, and while not as good as normal mice, the blind mice responded to light whereas before treatment, they didn’t.
“It was an international collaborative effort between scientists with a range of expertise,” says Awatramani. Using the novel, light activated molecule, channelrhodopsin, found in green algae, they were able to restore the mice’s sight. “We were able to target cells in the retina originally downstream of the photoreceptors. Once we expressed channelrhodopsin in bipolar cells the mice responded to light, albeit, their visual acuity was not as good as mice with normal vision,” says Awatramani. “It’s the first time a rescue of visual function with this strategy has occurred,” he adds.
Retinal degeneration is the leading cause of blindness and the research could have human benefits. “Restoration of vision with prosthetic devices is an emerging biotechnological niche with great potential,” says Dr. Steven Barnes, director of the Dalhousie Neuroscience Institute. “This advance holds real promise for restoring vision to people whose photoreceptors have degenerated,” adds Dr. John Dowling, professor of Neuroscience at Harvard.
Dr. Awatramani will continue retinal research at Dalhousie’s Retina and Optic Nerve Research Laboratory and will collaborate with Dr. Botond Roska in Switzerland. Current work targets the retinal circuits that are activated during increases of light. The next steps, he says, are to target the cells involved in dimming circuits in attempts to restore full vision. Clinical trials on humans will take place in Paris with the hope of restoring visual function in cases of human retinal degeneration.
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